// SPDX-License-Identifier: (GPL-2.0 or BSD-3-Clause-Clear)
  /**
   * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
   * All rights reserved.
   */
  
  /*-*************************************
  *  Dependencies
  ***************************************/
  #include "error_private.h"
  #include "zstd_internal.h" /* declaration of ZSTD_isError, ZSTD_getErrorName, ZSTD_getErrorCode, ZSTD_getErrorString, ZSTD_versionNumber */

  #include <malloc.h>

  #include <linux/kernel.h>
  
  /*=**************************************************************
  *  Custom allocator
  ****************************************************************/
  
  #define stack_push(stack, size)                                 \
  	({                                                      \
  		void *const ptr = ZSTD_PTR_ALIGN((stack)->ptr); \
  		(stack)->ptr = (char *)ptr + (size);            \
  		(stack)->ptr <= (stack)->end ? ptr : NULL;      \
  	})
  
  ZSTD_customMem ZSTD_initStack(void *workspace, size_t workspaceSize)
  {
  	ZSTD_customMem stackMem = {ZSTD_stackAlloc, ZSTD_stackFree, workspace};
  	ZSTD_stack *stack = (ZSTD_stack *)workspace;
  	/* Verify preconditions */
  	if (!workspace || workspaceSize < sizeof(ZSTD_stack) || workspace != ZSTD_PTR_ALIGN(workspace)) {
  		ZSTD_customMem error = {NULL, NULL, NULL};
  		return error;
  	}
  	/* Initialize the stack */
  	stack->ptr = workspace;
  	stack->end = (char *)workspace + workspaceSize;
  	stack_push(stack, sizeof(ZSTD_stack));
  	return stackMem;
  }
  
  void *ZSTD_stackAllocAll(void *opaque, size_t *size)
  {
  	ZSTD_stack *stack = (ZSTD_stack *)opaque;
  	*size = (BYTE const *)stack->end - (BYTE *)ZSTD_PTR_ALIGN(stack->ptr);
  	return stack_push(stack, *size);
  }
  
  void *ZSTD_stackAlloc(void *opaque, size_t size)
  {
  	ZSTD_stack *stack = (ZSTD_stack *)opaque;
  	return stack_push(stack, size);
  }
  void ZSTD_stackFree(void *opaque, void *address)
  {
  	(void)opaque;
  	(void)address;
  }
  
  void *ZSTD_malloc(size_t size, ZSTD_customMem customMem) { return customMem.customAlloc(customMem.opaque, size); }
  
  void ZSTD_free(void *ptr, ZSTD_customMem customMem)
  {
  	if (ptr != NULL)
  		customMem.customFree(customMem.opaque, ptr);
  }